Gold alloys



Patented Nov. 27, 1951 GOLD ALLOYS Joseph M. Williams, Attleboro Falls, Mass., assignor to Metals & Controls Corporation, Attleboro, Mass., a corporation of Massachusetts No Drawing. Application April 26, 1950, Serial No. 158,319

5 Claims. (Cl. 75134) This invention relates to alloys, and with respect to certain more specific features, to gold alloys.

This application is a continuation-in-part of my copending application Serial No. 88,905, filed April 21, 1949, entitled Gold Alloys.

The invention accordingly comprises the ingredients and combinations of ingredients, the proportions thereof, and features of composition, which will be exemplified in the products hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the manufacture of plated gold articles of jewelry, the gold plating is often quite thin, with the result that a problem is presented of providing a gold alloy for the plate which will resist abrasion when the article is being used or worn, it being difficult to provide a gold alloy with a high degree of wear resistance in a given karat which would have a color acceptable to the trade for that karat. The alloy which is the subject of this invention provides a metal which, for a given karat and color, has a desired degree of wear resistance.

Furthermore, during the manufacture of articles of jewelry from solid gold or gold plated stock, the material must oftentimes undergo bending or twisting or stretching operations. These operations tend to cause large grains or crystals of the metal to stand out in relief on the :1

surface of the alloy, giving the effect known as orange peel. In the alloy of the present invention, the grain structure is fine and of such nature as to minimize the production of orange peel.

A third, much desired characteristic of a gold alloy for the jewelry and allied industires is that of tarnish and corrosion resistance, especially Where the article will come in contact with perspiration and skin acids. This is one of the serious problems of the industry, and one solution for it in the past has been to make the alloy richer in gold content. This is naturally an expensive solution to the problem, due to the high cost of the gold. The alloy of the present iniacture of the gold alloy either as solid gold wire 66 or sheet, or as gold plated wire or sheet, the material is generally subjected to several heat treating or annealing operations. Also, during the manufacture of articles from such wire or sheet, the material oftentimes undergoes heat treating operations in whole or in part, such as in soldering, or brazing, or welding, operations, and the temperatures to which the alloy is subjected during such operations often equal or greatly exceed the normal recrystallization temperature of the alloy.

One of the factors governing the grain size in,

a metal during and after recrystallization, is the original grain size of the metal. It is also wellknown that cold working a metal distorts the original grain shape and sets up stresses therein, which become focal points for nucleation and subsequent new grain formation on recrystallization. If a metal is held at the recrystallization temperature over a long period of time, or is raised to temperatures higher than the recrystallization temperature for shorter periods, large grain growth is promoted. It is desirable, therefore, for the metal to have as high a recrystallization temperature as possible. In the alloy of this invention the temperature at which recrystallization takes place is raised, with the result that the alloy may undergo relatively high temperatures without adversely large crystals being formed. This results in an alloy which may undergo more severe heat treating operations without losing desirable qualities such as hardness, freedom from orange-peel, stiffness, etc., than can many hitherto known alloys.

The gold alloy of the present invention consists basically of gold, copper, iron and nickel.

The gold content depends upon the desired karat of the gold alloy. The present invention relates principally to alloys within the karat range of 8 to 20; hence the proportion of gold in the alloy, by weight, may vary from about 33% to about 84%.

The copper content may vary from about 10.7% to about 67%, by weight, of the alloy, depending upon the color, hardness, and other qualities desired of the alloy.

The alloy includes both iron and nickel, each of these metals being variable in the range .05% to 5%, by weight, the combined total weight of both the iron and nickel not to exceed 5% of the complete gold alloy, by weight. It is this combination of the iron and nickel that acts as the regulator of the grain size in the alloy, and holds it to a minimum. The preferred amount of each of the iron and nickel is about 1.25% by weight of the alloy.

With the exception of the alloys A and B, the following table gives the compositions of several specific alloys that have been made in accordance with the teachings of the present invention. Alloys A and B (prior art alloys) are given pri marily for comparative purposes.

Composition in per cent by weight Melt Karat Gold Copper Iron Nickel.

10 41. 66 58. 34 14 58; 33 41. 67 1O 41. En 55. 9 1. 25 L 25 8 33. 64. 1. 25 1. 25 12 50. 0 '47. 5 1. 25 1. 25. 14 58. 3 39. 2- 1. 25' 1. 25

- Approx. Hard-16$; Appearancaof(a)M.ErickSen; Gram 0000\360 m s s- OQQU! The superiority of the alloys made in accordance. with. the present invention (.C through. F) tothe typical prior art alloys (A and B) is evident.

In general, the best procedure for making the alloys of the present invention is first to make a base alloy X containing copper, iron, and nickel; these being. so proportioned that when added to the goldv no further copper, iron or nickel additions are required. However, it may be found that some alloys can bemade up more easily by mixing the components all together at the start.

For example, to make alloy 0, which is a karat red alloy of commercial importance, a first base alloy Xis made having about the following composition Percent Iron 2.4

Nickel e -1 2.4 Copper Balance Then using alloy X together with gold, silver and zinc, the final alloy is made up as follows:

. Percent Base alloy X 58.33 Gold 41.66

The eiiectof increasing the iron and nickel content is to produce an alloy having a. finer grain structure, greater resistance to wear and The I corrosion, and a higher recrystallization temperature, and a pronounced tendency to inhibit grain growth at commonly used heat treating temperatures.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results obtained.

As many changes could be made in the above alloys without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A gold alloy composed of the following metals in about the stated proportions:

Percent Gold .00! Copper 64.50 Iron 1.25 Nickel 1.25

2.. A. goldv alloy composed of the following metals in. about the stated proportions:

Percent Gold 41.66 Copper 55.83 Iron 1.25

3. A gold alloy composed of the following metals in about the stated proportions:

Percent Copper 47.5

Iron Nickel 1.25

4'. A gold alloy composed of the' following metals. in. about the stated proportions:

. Percent Gold 58.33 Copper 39.17 Iron. 7 r 1.25 Nickel. r 1.25

5. A gold alloy composed of gold, about 33 to 84% by weight; iron and nickel, each about .05 to 4.95 by' weight, with the combined Weight of iron and nickel not exceeding 5%; and balance copper, but not less than about 10.7% by weight.

JOSEPH M. WILLIAMS.

REFERENCES CITED The: following references are of record in the file oi this patent:

UNITED STATES PATENTS 

1. A GOLD ALLOY COMPOSED OF THE FOLLOWING METALS IN ABOUT THE STATED PROPORTIONS: 